Crystals
Kyanite
Aluminum silicate polymorph Al2SiO5 Triclinic crystal system High-pressure metamorphic mineral Strong directional hardness Perfect and good cleavage Blue, green, gray, white, black Rare orange variety Kyanite: Blue Blades Shaped by...
Kyanite
Aluminum silicate polymorph Al2SiO5 Triclinic crystal system High-pressure metamorphic mineral Strong directional hardness Perfect and good cleavage Blue, green, gray, white, black Rare orange variety Kyanite: Blue Blades Shaped by...
Ruby
Red corundum Al2O3 with Cr3+ Trigonal crystal system Mohs 9 No true cleavage Purplish-red to orangey-red pleochroism Marble, amphibolite, and basalt-associated deposits Rutile silk and six-ray stars Natural and laboratory-grown...
Ruby
Red corundum Al2O3 with Cr3+ Trigonal crystal system Mohs 9 No true cleavage Purplish-red to orangey-red pleochroism Marble, amphibolite, and basalt-associated deposits Rutile silk and six-ray stars Natural and laboratory-grown...
Coprolite
Fossilized fecal material Trace fossil and bromalite Phosphatic, carbonate, iron-rich, or silicified Bone, scale, shell, plant, and microfossil inclusions Pellet, segmented, spiral, and irregular forms Occasionally agatized and polishable Evidence...
Coprolite
Fossilized fecal material Trace fossil and bromalite Phosphatic, carbonate, iron-rich, or silicified Bone, scale, shell, plant, and microfossil inclusions Pellet, segmented, spiral, and irregular forms Occasionally agatized and polishable Evidence...
Malachite
Copper carbonate hydroxide Cu2CO3(OH)2 Monoclinic crystal system Mohs approximately 3.5–4 Specific gravity approximately 3.6–4.0 Light-green streak Botryoidal, fibrous, stalactitic, and banded Closely associated with azurite Acid- and ammonia-sensitive Malachite: Copper’s...
Malachite
Copper carbonate hydroxide Cu2CO3(OH)2 Monoclinic crystal system Mohs approximately 3.5–4 Specific gravity approximately 3.6–4.0 Light-green streak Botryoidal, fibrous, stalactitic, and banded Closely associated with azurite Acid- and ammonia-sensitive Malachite: Copper’s...
Larimar
Blue variety of pectolite NaCa2Si3O8(OH) Triclinic crystal system Mohs approximately 4.5–5 Radiating fibrous aggregates Sky, lagoon, and blue-green tones Hydrothermal veins in volcanic rock Barahona, Dominican Republic Larimar: Dominican Blue...
Larimar
Blue variety of pectolite NaCa2Si3O8(OH) Triclinic crystal system Mohs approximately 4.5–5 Radiating fibrous aggregates Sky, lagoon, and blue-green tones Hydrothermal veins in volcanic rock Barahona, Dominican Republic Larimar: Dominican Blue...
Jade
Umbrella term for two gem materials Jadeite: NaAlSi2O6 Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2 Both monoclinic Jadeite Mohs approximately 6.5–7 Nephrite Mohs approximately 6–6.5 Exceptional resistance to breakage Green, white, lavender, yellow, red-brown, and...
Jade
Umbrella term for two gem materials Jadeite: NaAlSi2O6 Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2 Both monoclinic Jadeite Mohs approximately 6.5–7 Nephrite Mohs approximately 6–6.5 Exceptional resistance to breakage Green, white, lavender, yellow, red-brown, and...